I've been playing with brad's cool backup utility brackup a bit, to store my CVS and SVN repositories on Amazon S3. So today, I got my first S3 bill: $0.05. I checked my credit card's website and sure enough, my available credit was reduced by five cents. (CapitalOne is very dilligent about reporting your available credit, but much slower about individual transactions.) I think for most merchants, charging you five cents would be a net loss, but maybe amazon has some kind of special deal.